The Unearthed Arcana Phoenix Bloodline Sorcerer can use a bonus action and trigger their ability for 1 minute, which reads:

Mantle of Flame

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Whenever you roll fire damage on your turn, the
roll gains a bonus to equal to your Charisma modifier.

Does this mean that, under this effect, a Scorching Ray deals 2d6+5 damage per beam (assuming 20 CHA)?

I specifically have in mind the other similar features in the game, the Draconic Sorcerer ability and the Evoker Wizard abilities, which allow their spellcasting mod to be added to damage as well. Also similar is the Warlock's Agonizing Blast invocation.

1 Answer
1

You have the right of it; each beam gets a boost

Whenever you roll fire damage on your turn, the roll gains a bonus to equal to your Charisma modifier.

Compare that to the Draconic Sorcerer's Elemental Affinity which states:

when you Cast a Spell that deals damage of the type associated with your draconic ancestry, you can add your Charisma modifier to one damage roll of that spell.

Spells like Scorching Ray which have multiple attacks will generate multiple damage rolls. Though they are all damage rolls of that spell, the rolls themselves are still separate instances of rolling damage. Since these are independent rolls and all occur on your turn, the Mantle of the Flame bonus would apply to each of them because it lacks a "one damage roll of that spell" clause.

For completeness, the Warlock invocation that you listed also lacks the "one damage roll of that spell" wording, which is why the boost there also applies to each beam of Eldritch Blast. The Evocation Wizard however has the same "one damage roll of that spell" stipulation that the draconic sorcerer has.